About this hybrid

For many years after the London plane-tree was discovered in London, England, its origins were shrouded in mystery. It was originally thought that London plane-tree was a natural variety of Oriental sycamore, Platanus orientalis, an introduced species from Asia, however it was never observed growing in the wild. It is now accepted that London plane-tree is in fact a hybrid between Oriental sycamore and the North American sycamore (Platanus occidentalis). Some botanists speculate that this hybridization occurred in the 1600s when a gardener to Charles I of England planted seeds of American sycamore that had been collected in Virginia. It is thought that one of these American Sycamores subsequently crossed with an Oriental sycamore growing nearby. Since that time, London plane-tree has been cultivated for planting in cities around the world and it is now one of the most widely planted urban trees.

Derivation of names

The genus name Platanus, is the classical name for the plane tree, from the Greek platus, meaning broad, in reference to the wide leaves. The species name, acerifolia, means maple leaf, in reference to the shape of the leaves. The symbol x in the Latin name indicates that London plane-tree is a hybrid species.

Related species

London plane-tree may be distinguished from the closely related American sycamore by the number of fruit clusters, and the bark. London plane-tree typically bears its round fruit clusters in groups of 2, while American sycamore usually bears solitary fruit clusters. American sycamore retains more of its flaky outer bark than does London plane-tree.

Similar species

London plane-tree leaves are similar to maple leaves because they are both palmately lobed. However all sycamores, including London plane-trees have alternate branch and leaf arrangement, while all maples have opposite branching. Sycamores have 3 main veins while maples such as Norway and sugar have 5 or 7 main veins. In sycamores, the leaf stalk encloses and hides the bud on the twig, while in maples, the bud is visible in a groove at the base of the leaf stalk. Sycamores bear round fruit clusters while maples produce winged keys (samaras). Sycamore maple (Acer pseudoplatanus), not a sycamore but a maple, is so named because it has similar leaves and multi-coloured flaky bark.

London plane-tree's place in Toronto's urban forest

London plane-tree's tolerance of urban conditions such as pollution, grime, salt and high pH soils led to it being very widely planted as a street tree; however the incidence of disease (see below) has reduced the frequency of planting in recent years.

Landscape value and potential for home use

London plane-tree's distinctive camouflage-patterned bark adds an interesting visual component, particularly in winter. Since it is a large tree with a spreading crown, it is only suitable for large spaces.

Pests and diseases: Trees may be affected by anthracnose, a fungal disease, when the leaves begin to emerge in spring. These leaves will be destroyed but will likely be replaced by a second crop of leaves. Repeated attacks of anthracnose can significantly weaken the tree. Cankerstain can be a serious disease, resulting in sparse foliage, cankers on the trunk with shoots growing at the site of cankers, and discoloration of bark at the site of a canker. The disease is spread by insects and by pruning equipment that has not been properly cleaned after contact with a diseased tree.

This tree is available for planting through the City of Toronto's street tree program.

Links to maps at Canadian Tree Tours:

• Toronto Island Park
• Trinity Bellwoods Park
• Queens Park
• High Park

• USDA Plants Profile (US Department of Agriculture)